context: remove dependency on reflect

Make context depend on reflectlite instead of reflect in effort to
eventually make net no longer depend on unicode tables.

With this CL we're down to just:

    net -> context -> fmt -> unicode tables

The next CL can remove context -> fmt.

Updates #30440

Change-Id: I7f5df15f975d9dc862c59aa8477c1cfd6ff4967e
Reviewed-on: https://go-review.googlesource.com/c/go/+/164239
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/context/context.go b/src/context/context.go
index 21a40d59477b4bc3277b4a2a036c9cb9e9d209b0..36f83c7b5b2b202708654a3d3840bc3af9da6394 100644 (file)
--- a/src/context/context.go
+++ b/src/context/context.go
@@ -50,7 +50,7 @@ package context
 import (
        "errors"
        "fmt"
-       "reflect"
+       "internal/reflectlite"
        "sync"
        "time"
 )
@@ -468,7 +468,7 @@ func WithValue(parent Context, key, val interface{}) Context {
        if key == nil {
                panic("nil key")
        }
-       if !reflect.TypeOf(key).Comparable() {
+       if !reflectlite.TypeOf(key).Comparable() {
                panic("key is not comparable")
        }
        return &valueCtx{parent, key, val}

diff --git a/src/go/build/deps_test.go b/src/go/build/deps_test.go
index df1d8dd3b373200b652640d0284e72b0fa3c24a8..e9ea0fabd80cfd559232ee02659a0ce8bcf5d0f3 100644 (file)
--- a/src/go/build/deps_test.go
+++ b/src/go/build/deps_test.go
@@ -249,7 +249,7 @@ var pkgDeps = map[string][]string{
        "compress/gzip":                  {"L4", "compress/flate"},
        "compress/lzw":                   {"L4"},
        "compress/zlib":                  {"L4", "compress/flate"},
-       "context":                        {"errors", "fmt", "reflect", "sync", "time"},
+       "context":                        {"errors", "fmt", "internal/reflectlite", "sync", "time"},
        "database/sql":                   {"L4", "container/list", "context", "database/sql/driver", "database/sql/internal"},
        "database/sql/driver":            {"L4", "context", "time", "database/sql/internal"},
        "debug/dwarf":                    {"L4"},
@@ -324,7 +324,7 @@ var pkgDeps = map[string][]string{
        // do networking portably, it must have a small dependency set: just L0+basic os.
        "net": {
                "L0", "CGO",
-               "context", "math/rand", "os", "reflect", "sort", "syscall", "time",
+               "context", "math/rand", "os", "sort", "syscall", "time",
                "internal/nettrace", "internal/poll", "internal/syscall/unix",
                "internal/syscall/windows", "internal/singleflight", "internal/race",
                "golang.org/x/net/dns/dnsmessage", "golang.org/x/net/lif", "golang.org/x/net/route",

diff --git a/src/internal/reflectlite/type.go b/src/internal/reflectlite/type.go
index 70c3723de79d01a07f5da02dd0371203ca765f5c..9767ffbd0d61b479ce767930793dc6e03f775072 100644 (file)
--- a/src/internal/reflectlite/type.go
+++ b/src/internal/reflectlite/type.go
@@ -44,6 +44,9 @@ type Type interface {
        // AssignableTo reports whether a value of the type is assignable to type u.
        AssignableTo(u Type) bool
 
+       // Comparable reports whether values of this type are comparable.
+       Comparable() bool
+
        // Elem returns a type's element type.
        // It panics if the type's Kind is not Ptr.
        Elem() Type
@@ -663,6 +666,10 @@ func (t *rtype) AssignableTo(u Type) bool {
        return directlyAssignable(uu, t) || implements(uu, t)
 }
 
+func (t *rtype) Comparable() bool {
+       return t.alg != nil && t.alg.equal != nil
+}
+
 // implements reports whether the type V implements the interface type T.
 func implements(T, V *rtype) bool {
        if T.Kind() != Interface {